This invention relates in general to concrete pavement and more particularly to a process and apparatus for supporting and stabilizing such pavement.
Much of the pavement in this country, whether it be at commercial, residential or institutional sites, takes the form of concrete slabs that have been poured directly over the underlying surface that they cover. Sometimes the underlying surface is not stable or washes away, in which case the slab is likely to sink. A sunken concrete slab not only fails to align with adjacent slabs, but often is not level or else does not possess the correct pitch.
Of course, a sunken slab may be broken apart, removed, and thereafter be replaced with a new slab which is poured in a like manner. Concrete work of this nature is quite expensive, and often the region in which it must be performed is not accessible to heavy concrete trucks.
Another corrective procedure, which is known as mud jacking, involves pumping a slurry of mud and cement at high pressure beneath the slab where it fills voids in that region and exerts an upwardly directed force on the slab. The force may be great enough to elevate the slab, but even so, the process is difficult to control. As a consequence, the slab may not rise to the desired elevation or may acquire an undesired pitch. Furthermore, the slurry, being at high pressure, is difficult to contain and may escape from the side of the slab. It may also find its way into sewer pipes and drains to perhaps block them.